1. Field of the Invention
This invention relates to methods of and apparatus for processing timecode data in a recorded digital video signal.
2. Description of the Prior Art
It has been proposed to record timecode information on a track of a magnetic tape in digital video recording. This allows for automatic searching for a particular frame on a tape by providing a unique address for each recorded frame. This facility is particularly useful in video editing. In one arrangement, the timecode is recorded on a longitudinal track of the tape adjacent to the oblique digital video tracks.
A problem with this arrangement, in particular when editing, is that the longitudinally-recorded timecode is difficult or impossible to read during slow-motion or freeze-frame replay. Accordingly, it has been proposed to include the timecode data in the video tracks, this being termed a vertical-interval timecode (VITC). Standards for VITC have been established by the US Society of Motion Picture and Television Engineers (SMPTE) and the European Broadcasting Union (EBU). However, during complex editing operations, timecodes from earlier generation recordings are lost, and therefore it is necessary to compile separate edit lists if historical records of the editing process are to be maintained. This information will be lost when a program is finally edited and the edit list destroyed.